Tarihin canjin yanayi. Lokacin da methane ya daidaita yanayin

Dama an ce haka nan canjin yanayi yana da ɗan zamani, sanadin galibi sanadin fitowar babban hayaki mai gurbata yanayi, kamar methane da CO2, ta mutane tun lokacin juyin juya halin masana'antu. Koyaya, menene zaku iya tunani idan na gaya muku cewa a cikin biliyoyin shekaru tun da Duniya ta samu akwai wasu canje-canje na yanayi?

Yanayin duniya ba koyaushe yake kamar yadda yake a yau ba. Ya kasance ta hanyar nau'ikan abubuwa da yawa. Menene tarihin canjin yanayi?

Lokacin da methane ya daidaita yanayin

Kimanin shekaru biliyan 2.300 da suka wuce, baƙon ƙwayoyin cuta sun hura sabuwar rayuwa a cikin duniyar "samari" ta lokacin. Labari ne game da cyanobacteria. Sun cika duniya da iska. Koyaya, an yi amannar cewa tun kafin wannan lokacin, wani rukuni na kwayoyin unicellular sun mamaye duniya kuma da sun sanya ta zama. Muna maganar methanogens.

Methanogens kwayoyin halitta ne masu rai guda ɗaya waɗanda zasu iya rayuwa kawai a cikin yanayin inda babu iskar oxygen kuma suna hada methane a yayin da suke aiki a matsayin kayan asuba. A yau zamu iya samun ƙwayoyin cuta ne kawai a cikin wurare kamar hanjin dabbobi, ƙasan ƙasa da sauran wurare a duniyar duniyar inda babu iskar oxygen.

Kamar yadda muka sani, methane is a greenhouse gas cewa yana riƙe da zafi sau 23 fiye da carbon dioxide, don haka ne ake tsammani cewa tsawon shekaru biliyan biyu na farkon duniya, methanogens yayi mulki. Gwargwadon ƙwayar methane da waɗannan ƙwayoyin halittar suka haifar ya haifar da sakamako mai gurɓataccen yanayi tare da babban sakamako a kan yanayin duniya.

A yau, methane yana ci gaba ne kawai a cikin yanayi na kimanin shekaru 10, saboda kasancewar iskar oxygen. Koyaya, idan yanayin duniya ba shi da ƙwayoyin oxygen, methane zai iya zama na kimanin shekaru 10.000. A wancan lokacin, hasken rana bai yi karfi kamar yadda yake yanzu ba, saboda haka adadin radiation din da yake kaiwa duniyar ta kuma yana dumama duniya, ya ragu sosai. Wannan shine dalilin, don ƙara yawan zafin jiki na duniya da ƙirƙirar yanayin zama, Ana buƙatar methane don tarko zafi.

Tasirin Greenhouse na wani tsohon yanayi

Lokacin da Duniya ta kirkira kimanin shekaru biliyan 4.600 da suka shude, Rana ta bada haske daidai da kashi 70% na abin da take yi a yau. Wannan shine dalilin da ya sa, kafin farkon shekarun kankara (kimanin shekaru biliyan 2.300 da suka gabata) yanayi ya dogara gaba ɗaya akan tasirin greenhouse.

Kwararru kan sauyin yanayi sunyi tunani a cikin ammoniya kamar iskar gas wanda ke riƙe da zafi a cikin ƙarancin yanayi, tunda wannan yana da ƙarfin gas mai ƙarfi. Koyaya, idan babu iskar oxygen, rawanin ultraviolet daga Rana yana lalata ammoniya cikin hanzari, yana mai sanya methane shine mafi girman gas a lokacin.

Zuwa gudummawar zafi a cikin sararin samaniya da sakamakon tasirin greenhouse kuma muna ƙara CO2. A lokacin, hankalinsa ya ragu sosai, wannan shine dalilin da ya sa ba zai iya zama sanadin tasirin greenhouse ba. CO2 kawai aka fitar dashi cikin sararin samaniya ta hanyar yanayi, ta hanyar aman wuta.

Matsayin methane da hazo wanda ya sanyaya duniya

Matsayin Methane wajen daidaita yanayin farko ya fara ne kimanin shekaru biliyan 3.500 da suka gabata, lokacin da methanogens suka hada gas na methane a cikin tekuna a matsayin kayan ɓarnata. Wannan iskar gas ɗin ta kama zafin Rana a cikin yanki mai faɗi da kebul na lantarki. Hakanan ya ba da izinin wucewar iskar ultraviolet, don haka a tsakanin waɗannan abubuwan da aka ƙara tare da CO2 na yanzu, sun kiyaye duniyar a yanayin zafin da ke zaune.

Methanogens sun rayu mafi kyau a yanayin zafi mafi girma. Kamar yadda yanayin zafi ya ta'azzara, haka nan aka sake zagayowar ruwa da zaizayar dutsen. Wannan aikin zaizayarwar duwatsu, yana cire CO2 daga yanayi. Don haka duka biyun ofididdigar methane da na CO2 a cikin sararin samaniya ya zama daidai.

Chemistry na sararin samaniya ya haifar da kwayoyin methane sunadarai (nau'ikan sarkar kwayoyin methane hade hade) da samar da hadadden hydrocarbons. Wadannan hydrocarbons sun hadu cikin barbashin da, a wuri mai tsayi, sun kafa lemu mai lemu.  Wannan gajimare na ƙurar kwalliyar ya biya sakamakon tasirin greenhouse ta hanyar ɗebe hasken da ke bayyane daga hasken rana da kuma sake watsa shi zuwa sararin samaniya. Ta wannan hanyar, ya rage yawan zafin da yake kaiwa saman duniyar sannan ya bada gudummawa ga sanyaya yanayi da kuma rage aikin samar da methane.

Tsarin thermophilic

Thermophilic methanogens sune waɗanda suka rayu cikin madaidaicin yanayin zafi. A saboda wannan dalili, lokacin da aka samar da hakar hydrocarbon, yayin da yanayin duniya ya yi sanyi kuma yake raguwa, thermophilic methanogens ba zai iya rayuwa da irin wannan yanayin ba. Tare da yanayin sanyi mai sanyi da kuma yawan tasirin yanayin zafi, yanayi ya canza a duniya.

Yanayin zai iya sanya abubuwan methane yawa sosai idan methane da an samar da shi a cikin saurin kwatankwacin na yanzu. Koyaya, methanogens basu samar da methane mai yawa kamar mutane a cikin ayyukan masana'antunmu ba.

Methanogens suna ciyar da abinci akan hydrogen da CO2, suna samar da methane azaman kayan ɓarnatarwa. Wasu wasu suna cinye acetate da wasu mahadi daban-daban daga lalacewar anaerobic na kwayoyin halitta. Abin da ya sa ke nan a yau methanogens Suna kawai bunƙasa ne a cikin tumbin dabbobi, dutsen da ke ƙarƙashin filayen shinkafa da ambaliyar ruwa, da sauran mahalli masu guba. Amma tunda yanayi na farko ba shi da isashshen oxygen, duk sinadarin hydrogen da dutsen mai fitarwa ke fitarwa an adana shi a cikin tekun kuma methanogens ne ke amfani da shi, tunda ba shi da iskar oxygen a wurinta don samar da ruwa.

Fog na "anti greenhouse" sakamako

Saboda wannan kyakkyawan yanayin sake zagayowar (mafi yawan zafin jiki, karin methanogens, karin methane, karin zafi, karin zafin jiki…) duniya ta zama irin wannan gidan haya mai zafi wanda ƙananan ƙwayoyin thermophilic ne kawai ke iya daidaitawa da wannan sabon yanayin. Koyaya, kamar yadda na ambata a baya, an sami hazo daga hydrocarbons wanda ke ɗaukar lamarin ultraviolet radiation sa yanayin yayi sanyi. Ta wannan hanyar, an dakatar da samar da methane kuma yanayin zafi da yanayin yanayi zai fara daidaitawa.

Idan muka kwatanta hazo da na Titan, babban tauraron dan adam na Saturn, Mun ga cewa shi ma yana da irin wannan yanayin lemu mai kama da layin danshi na sinadarin hydrocarbon, wanda ake samarwa lokacin da methane ya shafi hasken rana. Koyaya, wannan layin hydrocarbons din yana sanya saman Titan a -179 digiri Celsius. Wannan yanayin ya fi sanyi fiye da duniyar Duniya a duk tarihinta.

Idan gizagizan hydrocarbon na Duniya sun kai yawan nauyin da Titan yake da shi, da tuni ya sauya hasken rana da zai iya shawo kan tasirin iska mai karfin methane. Dukan saman duniyar zata daskarewa, don haka yana lalata dukkanin hanan adam. Bambanci tsakanin Titan da Duniya shine cewa wannan wata na Saturn bashi da CO2 ko ruwa, don haka methane yana bushewa da sauƙi.

Arshen zamanin methane

Hazo wanda ya samo asali daga methane bai dawwama ba. Akwai ƙyalli sau uku tun lokacin da Proterozoic da methane zasu iya bayyana dalilin da yasa suka faru.

Farin kankara na farko shi ake kira glaciation na Huronian kuma a ƙarƙashin tsofaffin duwatsun da aka samo a ƙarƙashin abubuwan da ke cikin ruwan sanyi akwai ƙarancin uraninite da pyrite, ma'adanai biyu da ke nuni da matakin ƙarancin iskar oxygen. Koyaya, sama da saman shimfidar ruwan sanyi, ana lura da dutsen yashi mai launin ja wanda yake ɗauke da hematite, ma'adinai da ake samu a ciki yanayin wadataccen oxygen. Duk wannan yana nuna cewa kyalkyalin Huronian ya faru daidai lokacin da matakan oxygen na farko suka fara tashi sama.

A cikin wannan sabon yanayin da ke cike da wadataccen iskar oxygen, sinadarai masu amfani da iska da sauran kwayoyin halittu wadanda a da suka mamaye duniyar, a hankali suka bace ko kuma aka gansu suna tauye wasu matsugunai. A zahiri, yawan methane zai kasance yadda yake ko sama da yadda yake a yau, idan da a ce matakan oxygen sun ragu.

Wannan yana bayanin dalilin da yasa a duniya, yayin Proterozoic, babu glaciations kusan shekaru biliyan 1.500, duk da cewa Rana ta kasance mai rauni sosai. An yi hasashen yiwuwar tashin na biyu a cikin iskar oxygen, ko a cikin narkar da sanadin mai, zai kuma haifar da yanayi na kyalkyali, ta hanyar rage kariyar methane.

Kamar yadda kake gani, yanayin duniya ba koyaushe yake ba kamar yadda yake a yau. Ya kasance ba shi da iskar oxygen (kwayar da muke buƙatar yau don rayuwa) kuma inda methane ke sarrafa yanayi da mamaye duniya. Bugu da kari, bayan dusar kankara, yawan iskar oxygen ya karu har sai ya daidaita kuma ya yi daidai da na yanzu, yayin da methane ya ragu zuwa wasu wurare da aka takura. A halin yanzu, adadin methane yana ƙaruwa saboda hayaƙi daga ayyukan ɗan adam kuma yana ba da gudummawa ga tasirin yanayi da sauyin yanayi na yanzu.